Page 12 - Lesson note-5-Ch 14 Statistics ( Measure of Central Tendency)

Median = [ +1 ]th value
2
By substituting the values
Median = [(9 + 1)/2]th value
Median = 5th value = 2x + 1
It is given that median = 55
We can write it as
2x + 1 = 55
2x = 54
x = 27
By substituting the value of x
2x + 1 = 2(27) + 1 = 55
So we get
52, 53, 54, 54, 55, 55, 55, 56, 57
We know that 55 occurs the maximum number of times so the mode is 55.